Radio signal circuits



. 1,613 733. Jan 11 1927 A. H. TAYLOR RADIOSIGN'AL CIRCUITS Filed Jam?, 1925- 2 Sheets-Sheet 1 A fz?. 1

' A. H. TAYLOR RADIO SIGNAL CIRCUITS Filed J an. '7, 1925 2 Sheets-Sheet 2 ation/w14 4 Patented Jan. 11, 1927.

unirse STATES 1,613,733A PATENT cerros.

ALBERT H. TAYLOR, OF WASIIINGTON, DISTRICT OF COLUMBIA, ASSIGNOR TO W'IRED RADIO, INC., 0F NEW YORK, N.V Y., A CORORATION OF DELAWARE.

RADIO SIGNAL CIRCUITS.

Application led January 7, 1925. Serial No. 1,054.

T he particular object of my invention is to provide a. radio frequency device to be used as a master oscillator or-as a heterodyne wa'iie meter whereby the frequency generated locally remains constant over a wide variation of vfilament current or of plate voltage or variations in the vcharacteristics of the tubes used.

A further object of my inventionis to provide a devicet-o be used in connection with the reception of radio frequency signals, especially signals'of very short wavelengths, that require a particularly constant frequency in the local oscillating circuits that autodyning with the incoming waves may be successl'ul.

l,Vith these andother objects in 7iew my y invention will be best'understood by reference to the accompanying drawing in which Figure l represents my invention 'as applied to a constantV frequency driver and Figures 2, 3, and 4 represent my invention as applied to radio -receiving circuits. Y

l represents a threey electrode vacuum tube, with grid leak 2 and grid condenser 3 connected as shown. When certain types ofv tubes, such as a -watt power tube is used, the grid condenser 3 may be short circuited with beneficial results.l The filament is heat ed by a'separate local battery as shown.

Referring more particularly to Figure l,

. coil 4 in the plate circuit and coil 5 in the timing circuit are fixed in value and posi* tion. Condenser 6, which performs the function of exciting and controlling the grid may be kept at a fixed value, or it may be varied in such a manner as to keep its alue always several times larger than the condenser 7. Tuning is accomplished by condenser 7, and sometimes also by condenser which condensers should be of a precision type. For extremely wide ranges of tuning it may be necessary to provide switches to vary the inductance in coils 5 and 4 but during operation over normally Wide ranges of frequency the inductances 5 and 4 are fixed and tuning is accomplished solely by var fino the condensers 7 and 6. The mutual inductance between coils 5 and 4 will be different for the different values of the inductances of each coil but as the coils remain immovable and the inductanf-e of the coils are not changed during tuning, the mutual inductance will remain constant for any definite range of frequencies. The grid coil ll.

leak, which must be connected between the grid and the filament', should be of somewhat smaller value than is customary. The power for the plate circuit may be from any external direct currentsource, such as the battery 8. Condenser 9 is in parallel with the battery to provide a low impedance path for the high frequency oscillations. A telephone may be inserted at l() to give an indication, by. a click, as to when the circuit is oscillating or in case this invention is used in connection with a receiving circuit, an audiorrequeney responsive apparatus is connected at this point. Hot wire ammeters may be placed in the plate and grid circuits to indicate any unusual conditions, suchv as abnormal plate current or abnormal grid current due to the use of a defective tube.

It will be seen that the grid excitation voltage, being obtained `byusing the drop of potential across 4the condenser 6, is practically independent of the frequency. If the frequencyv rises, the indiiced vvoltage across coils 5 and 4 increases but at the same time theA drop across the excitation condenser 6 vper unit of current in condenser 6 falls. If the grid is taking normal exe citation, this can remain constant only when the current in the main oscillating circuit is itself constant. Furthe more, as the grid excitation voltage is particularly independent of the frequency, the frequency, also, is almost completely independent of the temperature of the filament, and of the voltage of the plate battery 8. Tubes may be interchanged in this circuit with but little effect on the frequency even when they are of different types.

My invention7 as applied to receiving cir- -cuits using the autodyne system of reception of continuous wave signals, is shown in Figures 2, 3, and 4. In Figure 2 the signal receiving circuit is coupled to the coil l2 in the secondary circuit by means of When the coupling between 1l and l2 is loose, the tuning of the signal receiving circuit has no effect on the frequency of the local oscillating circuiti.`

ln Figure 3 the signal receiving circuit is coupled to coil l2 in the plate circuit by coil ll. Then the coupling between ll and l2, is loose, the tuning of the signaling circuit has no effect on the frequency of the local oscillating circuit.

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qu' u In the circuits as set forth in Figures 2 and 3 control of regeneration is obtained by altering the coupling bet-Ween coils ll and l2. lf this coupling is tightened up to the point Where oscillations cease, the frequency will change but one or two kilo cycles at short Waves, but this change is not enough to throw the signals out of tune. The detuning never amounts to more than li of one per cent. This permits non-oscillatory reception at the san-1e calibrated settings as used for C. lV. reception, by simply making the coupling tight enough to stop oscillation.

In Figure @i the sign-al receiving circuit is coupled by means of coil ll to coil l2 in series with the grid leal; 2. This arrangement gives the most constant frequency and even when a tight coupling exists between ll and l2 tuning in the receiving signal circuit has no effect Whatever on the local frequency generator. However, this circuit can be used only for reception of continuous wave signals as there is nov Way of controlling the regeneration except by changes of filament temperatures, which is considered unsatisfactory.

That l claim is:

l. A generator of high frequency electrical oscillations comprising in combination an electron tube having grid, filament and plate electrodes, input and output circuits interconnecting said electrodes, an inductance included in each of said circuits and coupled one to the other, the inductan-ce in said input circuit being connected in series With a pair of condensers, one of sani condensers being connected in shunt with said input circuit for controlling the excitation of sai-d grid independent of variation in frequency.

2. A system for generating high frequency electrical oscillations comprising in combination. an electron tube having grid, filament, and plate electrodes, input and output circuits interconnecting said electrodes, a pair of mutually coupled inductances, one connected in said input circuit and the other connected in said output circuit,` a pair of condensers arranged in series with the inductance in said input circuit7 one of said condensers having a substantially larger electrical capacity than the other, and a parallel connemn between said last mentioned condenser and said input circuit.

A system for generating high frequency electrical oscillations comprising in coin:- binationan electron tube having' grid, filament and plate electrodes, input and output circuits interconnecting said electrodes, a pair of mutually coupled inductances, one connected in said input circuit and the other connected in said output circuit, a pair of condenser-s, one of said condensers being connected in series with said input circuit, and the other of said condensers being connected in shunt with said input circuit, said last mentioned condenser having a value subslantially larger than. said lirst mentioned condenser.

ALBERT H. TAYLOR, 

